VBA to find first available slot

Hi,

I was wondering if it'd be possible for Excel to find the next available spot for job that needs to be completed.

Screenshot 2021-06-09 083244.jpg

For example, I'd like Excel to change the highlighted start time to 4:00 pm as the previous job is scheduled till 3:45pm. Eventually, jobs won't be sorted, so it'd be awesome if Excel could find the first available slot for its start sate & time.

Thanks for your help.